The present invention relates to cosmetic product compositions exhibiting the ability to moisturize human skin and leave the skin feeling soft and supple for extended time periods. In particular, it relates to the use of naturally occurring and/or synthesized vernix lipid mixtures in the same proportionate mixture. The vernix composition is composed of a specific ratio of fats commonly known as saturated fats at about 1 part, fats commonly known as monounsaturated fats at about 1 part, fats commonly known as polyunsaturated fats at about 0.25 parts, fats commonly known as phosopholipids at about 4 parts, fats commonly known as glycolipids at about 2 parts and minor quantities of fats known as aminolipids and waxes.
The vernix (commonly known as vernix caseosa or vernix caevsa) is a cheesy deposit on the surface of a human or animal fetus derived from the stratum corneum, sebaceous secretion, and remnants of the epitrichium. This naturally occurring deposit is of a specific composition with extraordinary properties for keeping the fetus' skin soft and moist.
Heretofore, individual fatty compositions and/or types of lipids have been utilized in various compositions having some skin moisturizing property. However, various side effects such as irritation, sensitization, odor, greasy feeling, acne, comedogenicity, and allergic effects, have been experienced.
It is well recognized that the most important function of the human skin is to protect the body from adverse environmental factors which tend to dry and flake the skin. This barrier of skin derives some added protection from the complex lipid layer that covers the skin surface and extends over the surface of skin. The natural lipid layer slows down the absorption of foreign substances at least for short contact periods, and it confers to the skin water shedding properties.
Some alterations of the normal properties and functions of skin interfere with its barrier qualities. Exposure of the skin to low humidity such as that found in heated buildings in winter, various detergents, and soaps, industrial chemicals, solvents, wind, cold, heat and sun may at times damage the skin. Protection such as applying oils, petrolatum, various creams and lotions containing moisturizers prevent water loss from the skin's surface. However, apparent side effects may also occur affecting the skin's properties or functions in deeper skin layers.
It is further recognized that if the skin is damaged due to some external effect which causes dryness to occur it is unable to function as a protective barrier. The lipid film on the surface of the skin is of major importance in maintaining flexibility and in keeping the skin barrier integral for preventing dryness. Absence of the moisturizing lipids causes dehydration, resulting in chapping.
The lipid layer on the skin is composed of a hydrophilic mixture of free and esterified cholesterol, other sterols, fatty acids, waxes, fats and hydrocarbons. Cholesterol is hydrophilic, however its esters are hydrophobic. Therefore, the lipid film participates in a dual function. The hydrophobic deeper layers of the skin shed water while the hydrophilic outer layers retain water in an emulsified form to maintain the skin generally soft and supple.
The main characteristic of the skin's lipid layer is manifested in the intense interest focused in finding suitable materials to supplement its moisturizing ability. Lanolin has been suggested for this purpose, since the skin's surface lipids of all mammalian species were thought to be similar to that of humans. However, there are marked differences in composition between lanolin and the lipid layer on the surface of the human skin. Lanolin is composed of hydrophobic esters which oppose absorption of water whereas human skin lipids are hydrophobic and hydrophilic as well.
Moisture loss from the skin can be reduced by using water repellant films such as petrolatum but it can cause maceration by preventing even normal moisture loss from the skin. Various lanolin derivatives are used in order to obtain more hydrophilic effects than lanolin and obtain water-resistant films purported to be less occlusive than petrolatum. These products function as skin lubricants as well. However, lanolin has been reported to cause allergic reactions in a high number of individuals.
There is another classification of moisturizers which are water soluble and generally referred to as demulcents, which are glycerine, sorbitol and various other polyols. These substances hold water in close contact with the skin and thus supply water to the epidermis. These agents also supply a softening effect on the skin when applied at suitable concentration and in suitable vehicles.
There are fats and oils of vegetable and animal origin which are used in cosmetic formulations for their emollient, occlusive properties and moisturizing properties. However, problems such as stability of these products require use of additives or stabilizers which in turn have caused dermal problems resulting from the stabilizers used in the cosmetic formulation. Phospholipids have also been used in various creams and lotions as moisturizers. These lipids are complex fat substances found in living cells. Lecithin is an example of a typical phospholipid substance. The classical moisturizer has always been recognized as cold cream based upon oils in a cream form.
Many of the ingredients already discussed are used for their moisturizing properties. However, because the conservation of body moisture has been associated with beauty care, a host of specialized cosmetics has been created exclusively for this purpose. They may be known under various names such as hand and body lotions, day creams, facial moisture creams, nail moisturizers, complexion lotions, etc. Despite such apparent diversity, they all work in pretty much the same fashion. To understand the common features of these products (and all secondary moisturizers like cold creams), one must look at the clinical problems that justifies their use.
Dry skin affects most people at some point in their lives, particularly the older and light-skinned. Usually, it occurs on hands and legs and, to some extent, the face. Even though it is known that loss of the skin's moisture leads to flaking, chapping, or other irritation of body surfaces, no one knows precisely how to define the problem--not even dermatologists and cosmetologists.
The oily secretions of the sebaceous gland seem to help protect the skin from foreign substances. These secretions, in conjunction with sweat, form a smoothing film that supplies skin with luster, depth of color, and an evaporation barrier. The scalp, face and shoulders have abundant amounts of sebaceous glands. Other portions of the body have fewer glands and are more susceptible to drying out. Hands and legs are doubly vulnerable because they produce little oil and are frequently exposed to harsh weather and chemicals. Scientific studies seem to indicate that only two moisturizers cause significant long-term improvements. These are lanolin and petroleum jelly (petrolatum). For short-term relief from dry skin, such as that resulting from washing, exposure to drying conditions, almost any commercial product works.
It is apparent from consumer studies that moisturizing preparations do have limited value in helping dry skin among certain people at certain times. Older persons with diminishing secretions from their sebaceous glands may well want to use a product containing petroleum jelly or lanolin. the usefulness of moisturizers for the rest of the population, however, is doubtful. As in the case of cold creams, facial lotions can clog pores that eventually fester when such products are applied too frequently.
While it is not exactly clear how moisturizers work, dermatologists and cosmetologists do know that oil is the key to all lubricating, moisturizing, and softening products. Without oils, these preparations would be ineffective, even though oils have no ability to moisten skin. They do, however, somehow help the skin remoisturize itself.
The oils or emollients found in these products may be as commonplace as lard or peanut oil, a little more refined like mineral oil and petrolatum, or more complex laboratory discoveries such as dimethicone and synthetic spermaceti. Whatever the oil used in a lotion, it will, to some extent, mask the effects of dry skin by lubricating and smoothing the skin's inherently rough surface.
Petrolatum and lanolin head the list of effective emollients. Both of these substances are commonplace and relatively inexpensive. (Some people are allergic to lanolin.) However, the cosmetic industry has abandoned simplicity for elaborate formulations full of various ingredients. Some of these more sophisticated and expensive creams and lotions may have an attractive scent and feel less greasy than plain petroleum jelly. However, unless they contain this basic emollient or lanolin, they will probably prove to be ineffective in the long run.
Water is even more of a common denominator in moisturizing cosmetics than oils are. This water has nothing to do with moisturizing the skin, but rather with providing good consistency and spreadability of the product. Products containing water usually have humectants to prevent evaporation that would leave the cream too thick or hard. These water retainers help keep lotions usable over a long time, but they apparently do not attract needed moisture to dry skin. But some humectants do serve a useful function as emollients.
Preservatives are another type of ingredient required in many water-oil emulsions. Certain types of natural oils and water combine to form a favorable environment for the growth of microorganisms. Without preservatives, products contaminated with bacteria could possibly lead to infection of sensitive areas like abraded skin or the eyes. The more complex moisturizers contain a number of other substances that are totally unrelated to the effectiveness and preservation of the formulation. Among such are thickeners, which are added because some consumers associate rich, heavy creams with luxury and moisturizing power. There are also emulsifiers to hold the water and oils together.
Once again, it is important to mention the potential side effects of moisturizers for producing acne. But there are other hazards connected with these products that have not received as much public attention. Allergies are a case in point. Any cosmetic frequently applied to large areas of skin and composed of endless varieties of chemicals will inevitably cause trouble for at least some users--particularly when it is left on the skin, as most skin products are. The longer toxic chemicals remain on the skin, the greater the chance of their causing harm to the skin surface.
A number of common ingredients in skin creams that most frequently trigger allergies and cause skin irritation among consumers. However, many of these substances are not essential to a good moisturizing preparation. The inclusion of lanolin in moisturizers may pose a problem for consumers. This natural oil is an excellent long-term lubricant of the skin, but some people are allergic to it. Moisturizer containing safer, derivative compounds from lanolin, such as acetylated lanolin, may be used.